The Echelsbacher bridge has spanned the deep Ammer Gorge at heights of up to 80 m above the valley for over 90 years with an arch span of 140 m. It has a total length of 182 m and connects the communities of Bad Bayersoien and Rottenbuch in the south-west of Upper Bavaria. The B 23 federal road leads over the Echelsbacher bridge, running from Peiting to the German-Austrian border near Griesen. The project, known as the ‘B23 construction project, partial restoration of Echelsbacher bridge’, was implemented between 2017 and 2021 in order to secure the structure and preserve it for the future. 

The bridge was erected in 1929 with the Melan- Spangenberg construction system and the world’s largest bridge arches of their kind. This construction method, developed by the Austrian structural engineer Joseph Melan (1853 – 1941) and adapted by Prof. Heinrich Spangenberg (1879 - 1936) for large spans, involves a free-standing steel trussed arch being erected before internal and external casing is attached and concrete is filled in segments. The ‘B23 construction project, partial restoration of Echelsbacher bridge’ was already preceded by four restorations.

What was likely Germany’s largest temporary bridge allowed traffic along the B 23 to continue moving during construction work on the partial restoration between 2019 and 2021. The listed arches were preserved on the main structure while damaged areas were removed and repaired. The remaining old bridge was demolished. In addition to the existing arches, a new arch with a similar support system was erected. New railings were installed on the bridge coping that consist of filigree steel blades that appear to float freely. The railings prevent falls and climbing in accordance with safety requirements and ensure that people don't fit between the openings of the bars. 

The structural engineering planners opted for a fixing solution by the fischer Group of Companies to securely fasten the specially designed, 2.50 m high steel railings to the concrete bridge coping. The fischer injection mortar FIS HB was used together with approx. 2,500 stainless steel fischer anchor rods FHB II AL M16x160 A4. The work was carried out by the Munich firm Schallschutz Schröder GmbH. The system allows heavy loads to be securely anchored in concrete. Further assurance is provided by the ETA Option 1 for cracked concrete and the Swiss shock approval. The performance of the styrene-free vinyl ester mortar combined with the corresponding anchor rod with its optimised cone geometry results in a high level of cost efficiency, as fewer fixing points and smaller anchor plates are sufficient in order to achieve a secure hold. The combination of the injection mortar FIS HB and the anchor rod FHB II is particularly suitable for outdoors series installation. 

“In addition to the performance capacity of the chemical fixing system, our client was also impressed by our wide range of services with which we successfully accompany them throughout the various construction phases”, says Günter Seibold, Head of Application Engineering at fischer Deutschland Vertriebs GmbH. “Our support ranged from consultation and design to briefing and on-site training until the installation project was completed safely and successfully”. Christian Felch, Field System Consultant at fischer Deutschland Vertriebs GmbH, adds: “Joint solutions were also used again and again in the detailed process, fulfilling the needs and requirements of our customer’s project – be it corner connections, installation aids, drilling templates or methods to carry out the fastenings exclusively using prepositioned installation”. 

Germany’s federal road network currently includes around 40,000 bridges, according to the BMVI (Federal Ministry of Transport and Digital Infrastructure), many of which require renovation. One of the reasons for this is the fact that many of the bridges are old. Large valley bridges in particular were often erected at least 50 years ago. Another reason is the increase in traffic, especially heavy goods vehicles. Regular inspections and renovations, if necessary, are therefore required in order to prevent catastrophes such as the collapse of the Morandi bridge in Genoa, Italy. Construction measures such as the ‘B23 construction project, partial restoration of Echelsbacher bridge’ therefore make an important contribution to the safety of people and infrastructure.